Cisco 7906G Administration Guide - Page 243

Chapter 9 Troubleshooting and Maintenance Monitoring the Voice Quality of Calls Table 9-4 Changes to Voice Quality Metrics Metric Change Condition MOS LQK scores Network impairment from packet loss or high jitter: decrease significantly • Average MOS LQK decreases could indicate widespread and uniform impairment. • Individual MOS LQK decreases indicate bursty impairment. Cross-check with Conceal Ratio and Conceal Seconds for evidence of packet loss and jitter. MOS LQK scores • Check to see if the phone is using a different codec decrease significantly than expected (RxType and TxType). • Check to see if the MOS LQK version changed after a firmware upgrade. Conceal Ratio and Conceal Seconds increase significantly • Network impairment from packet loss or high jitter. Conceal Ratio is near or at zero, but the voice quality is poor. • Noise or distortion in the audio channel such as echo or audio levels. • Tandem calls that undergo multiple encode/decode such as calls to a cellular network or calling card network. • Acoustic problems coming from a speakerphone, handsfree cellular phone or wireless headset. Check packet transmit (TxCnt) and packet receive (RxCnt) counters to verify that voice packets are flowing. Note Voice quality metrics do not account for noise or distortion, only frame loss. OL-14585-01 Cisco Unified IP Phone 7906G and 7911G for Cisco Unified Communications Manager 6.1 9-27